"Generator Buffer" function?

[JP16A60]

Greetings, all.

I'm considering the purchase of some electronics training boards for use with the Lab-Volt FACET system (see http://www1.labvolt.com/publications/product_guides/94004_00.pdf for more info), but I'm stumped about one of the hardware requirements.

Several of the boards have a placeholder for a "generator buffer"; the Lab-Volt literature describes this module as being "...required for generators used in lab experiments not having an output impedance of 50 ohms."

Some of the trainer boards with this requirement include:

91010-20 FET Fundamentals (ex. http://www.ebay.com/itm/Lab-Volt-91010-20-FET-Fundamentals-Trainer-Board-AS-IS-UNTESTED-/391552908055)
91007-20 Transistor power Amplifiers (ex. http://www.ebay.com/itm/Lab-Volt-91007-Transistor-power-Amplifiers-Course-Circuit-Board-Labvolt-FACET-/122100547711)
91005-20 Semiconductor Devices (ex. www.ebay.com/itm/Lab-Volt-91005-20-Semiconductor-Devices-Trainer-Board-w-Base-Unit-/351831293176)
91003-20 AC 1 Fundamentals (ex. www.ebay.com/itm/Lab-Volt-91003-20-AC-1-Fundamentals-Course-Interface-Training-Board-682-/321858764993)

My assumption it that this "generator buffer" is a required component to fully leverage these training boards, but I have had no luck in finding such a component on eBay (nor much else in the way of even basic documentation).

The Big Question^TM: Does anyone here have a decent notion of what this thing does, or what/how I might create or locate some reasonable substitute? 

Last-minute thoughts: Maybe I'm a bit dense, but: 1.) Is the "generator" mentioned simply referring to a standard "function generator", and if so, 2.) Do typical mid- to high-end Tektronix and/or HP function generators feature 50 ohms output impedance?

JP

[Dave]

The generator buffer is just a buffer amplifier with a 50R input impedance and a low output impedance.

Yes and yes to your last two questions.

50 ohm impedance is required to properly terminate signals to prevent reflections and all of the other nasties. Those only come into play with higher frequencies, so I imagine that whoever designed your training course, decided on the buffer amplifier to simplify things, so your function generator becomes an approximation of an ideal one, instead of having to keep thinking of the output impedance.

[JP16A60]

Awesome--that makes perfect sense now. Thanks, Dave!

JP

[edavid]

The generator buffer is just a buffer amplifier with a 50R input impedance and a low output impedance.

I think it probably has a high impedance input and 50ohm output impedance.

Yes, most lab function generators have 50ohm output.